Abstract: A plug valve is disclosed having one or more components that are coated to reduce wear on the components. A plug of the valve may include a bore therethrough defined by an inner surface of the plug. The inner surface of the plug may include a nitride layer, such as a carbonitride layer. An outer surface of the plug may include both a nitride layer, in addition to a thermal spray coated layer, such as WC. The nitride layer may be formed by a ferritic nitrocarburizing process and the thermal spray coating may be formed by a high velocity air fuel (HVAF) or similar process. Inserts of the plug valve may also be coated by similar processes. An outer surface of the inserts may have a nitride layer and an inner surface of the inserts may have a nitride layer and a thermal spray coating.

Abstract: A ride control system includes four independent metering valves (IMVs) that are independently and selectively controlled by a controller for attenuating oscillations in a hydraulic actuator of a machine. The controller is configured to open at least one of the IMVs for supplying pressurized fluid from a tank to a head end chamber of the hydraulic actuator when a pressure of the head end chamber drops to a value less than an initially registered pressure. Additionally, when the displacement of the piston block is positive and the pressure in the head end chamber falls to a value less than the pressure of fluid in a rod end chamber of the hydraulic actuator, the controller may also open another one of the IMVs by which fluid from the rod end chamber could be supplied to the head end chamber for supplementing pump flow and attenuating oscillations in the hydraulic actuator.

Abstract: A ride control system includes four independent metering valves (IMVs) that are independently and selectively controlled by a controller for attenuating oscillations in a hydraulic actuator of a machine. The controller is configured to open at least one of the IMVs for supplying pressurized fluid from a tank to a head end chamber of the hydraulic actuator when a pressure of the head end chamber drops to a value less than an initially registered pressure. Additionally, when the displacement of the piston block is positive and the pressure in the head end chamber falls to a value less than the pressure of fluid in a rod end chamber of the hydraulic actuator, the controller may also open another one of the IMVs by which fluid from the rod end chamber could be supplied to the head end chamber for supplementing pump flow and attenuating oscillations in the hydraulic actuator.

Abstract: A hydraulic system and methods for conserving energy in such system is disclosed. The hydraulic system includes a hydraulic actuator having a head end, a rod end and a piston disposed therebetween. The system also includes a pump that pumps fluid to the actuator, a first valve disposed downstream of the rod end, and a second valve disposed between the pump and the head end of the actuator. When the system is in a load overrunning condition, the second valve is partially closed to restrict the flow of a combined fluid. The combined fluid including fluid received from the pump and fluid received from the rod end of the actuator. When the system is in the light resistive load condition, the second valve is open to allow the combined fluid to flow through the second valve.

Abstract: A method and system for accumulating and using recovered hydraulic energy that includes a hydraulic actuator and a pump configured to supply pressurized fluid to the hydraulic actuator. An energy recovery system includes a hydraulic motor, a charge valve and an accumulator configured to store fluid from the hydraulic actuator. The charge valve is operatively connected between the hydraulic actuator and the accumulator and between the accumulator and the hydraulic motor and is configured to place the hydraulic actuator in fluid communication with the accumulator and to place the accumulator in fluid communication with the hydraulic motor. A directional valve is operatively connected between the pump and the hydraulic actuator. The directional valve is configured to place the pump in fluid communication with the hydraulic actuator and to direct the flow of hydraulic fluid exiting the hydraulic actuator to the charge valve in an energy recovery mode.

Abstract: A hydraulic system and methods for conserving energy in such system is disclosed. The hydraulic system includes a hydraulic actuator having a head end, a rod end and a piston disposed therebetween. The system also includes a pump that pumps fluid to the actuator, a first valve disposed downstream of the rod end, and a second valve disposed between the pump and the head end of the actuator. When the system is in a load overrunning condition, the second valve is partially closed to restrict the flow of a combined fluid. The combined fluid including fluid received from the pump and fluid received from the rod end of the actuator. When the system is in the light resistive load condition, the second valve is open to allow the combined fluid to flow through the second valve.

Abstract: A method and system for accumulating and using recovered hydraulic energy that includes a hydraulic actuator and a pump configured to supply pressurized fluid to the hydraulic actuator. An energy recovery system includes a hydraulic motor, a charge valve and an accumulator configured to store fluid from the hydraulic actuator. The charge valve is operatively connected between the hydraulic actuator and the accumulator and between the accumulator and the hydraulic motor and is configured to place the hydraulic actuator in fluid communication with the accumulator and to place the accumulator in fluid communication with the hydraulic motor. A directional valve is operatively connected between the pump and the hydraulic actuator. The directional valve is configured to place the pump in fluid communication with the hydraulic actuator and to direct the flow of hydraulic fluid exiting the hydraulic actuator to the charge valve in an energy recovery mode.

Abstract: A hydraulic system is disclosed that includes a hydraulic actuator having a head end, a rod end and a piston disposed therebetween. The system also includes a pump configured to supply fluid to both ends of the actuator. The system also includes an energy conservation system that is configured to reduce flow from the pump to the head end of the actuator and to increase flow from a make-up fluid circuit to the head end of the actuator during an overrunning load condition. The energy conservation system also increases flow from the pump to the head end of the actuator and decreases flow from the make-up circuit to the head end of the actuator after the overrunning load condition has ceased.